Bitter Principles, substances extracted from plants by digestion in water, alcohol, or ether, and which possess in concentrated form that which gives the bitter taste to plants. Excepting this, these extracts do not appear to possess other characteristic properties in common; their nature, however, is not very well understood. Many alkaloids, especially quinia and strychnia, possess an intense bitterness, but are not classified with the substances just described, because they possess other much more important properties. Some bitter principles are crystallizable, as colombine, quas-sine, gentiopicrine, taraxacine, aloine, and phloridzine, a substance obtained from the bark of the apple, pear, and cherry; while the bitters of hops, pinkroot, and wild cherry have not yet been obtained in crystals, and that of the last mentioned drug not even isolated. Some of the numerous varieties of bitters are soluble in water; some only in alcohol or ether. They are generally neutral in their properties, uniting neither with acids nor bases. - Bitters are used in medicine as tonics, and also as aperients; and in the manufacture of malt liquors they are employed to impart to them their bitter flavor.
In the healthy condition bitters do not assist or accelerate digestion, but rather the contrary, as has been shown by direct experiment. When the digestion is enfeebled, however, they seem to impart vigor to this process by stimulating the flow of gastric juice and by retarding the progress of abnormal fermentations, which have a tendency to take the place of and interrupt the healthy process. The sensation produced by the irritation of bitters in the stomach should not be mistaken for true hunger.